New guy with an RTV 1100 Problem

Ster1

New member
Hello!
My name is Pete, and I live near Denver CO. I'm a mechanic, and I work on mostly construction machinery like loaders and such.

Today, however I have something new, as in new to me. A Kubota RTV1100; I believe it's a 2006 or 2007 model. Older one. I believe it's called the worksite model. It has a dump bed, a V plow with full joystick control and a tandem hydraulic pump running off the accessory pad on the engine.

I pulled the engine (and hydrostat) to service the engine and when I put it back together, it started acting odd. What's happening is, within about 30-40 seconds of startup, the hydraulic system pressures out and kills the engine. Engine runs just fine. I noticed the flex hose to the front (main?) pump segment is the one that's pressuring out. The engine starts, the hose stresses, the engine dies, the hose relaxes. Rinse... repeat. I looked on Kubotabooks and they don't have the right book for this old of an 1100, so I may have to buy one. In any case, I'm assuming the front or main section of the pump runs the dump and steering, and the aux or rear section runs the plow. Again, I don't have the book (yet); that's just an assumption. I bypassed the dump system (more or less) by taking the quick disconnects off the hard lines in the rear of the machine and just shorting them with a section of hose. If any flow goes that way, it should return to tank. So that leaves just the steering as the issue? When I turn the steering wheel the wheels do turn, but I feel significant feedback "wobble" in the wheel, as if I was going fast over rocks (that's kinda what it feels like). Real wierd, because I'm not moving and the front wheels are raised off the floor.

Anyway, are my assumptions about the circuits in general correct? If so, I have to look at the pressure in the steering system. Maybe my relief isn't relieving. Definitely something odd going on.
 
I did some more digging today. Firstly, I was incorrect about some assumptions. The front section of the pump appears to only power the plow. The rear section of the pump is apparently for steering and dump, which seem to be working fine (aside from the wobble, but I'll worry about that later). What's happening is the plow, it seems, is pressuring out the system, at about 5K psi. Here's a little vid of what's going on.


The system should never reach 5K, so there's definitely a relief problem there, at least. I would guess the issue is electrical, but even with the entire plow disconnected electrically, it still happens. Also, I noticed a 3rd hose going to / from the plow. I know why there would be 2 hoses, but why the 3rd one? I mention this because that one might be flexing too, I can't be sure yet though. That suggests there might be something downstream from the plow causing the issue or making it worse. Without documentation though, I'm kinda in the wind.

I'm trying to get my local dealer to sell me the documentation for the plow, but he can't even identify it yet. He tells me that the attachments are "hit and miss" as far as documentation goes (!?). I have the install manual for the mechanical portion of the plow, but I need info on those hydraulics! Frustrating.
 
Correct. That pump has nothing to do with the transmission. Apparently it is dead heading and killing the engine? Since it idles and then suddenly dies i suspect that you are actuating the blade?
 
Correct. That pump has nothing to do with the transmission. Apparently it is dead heading and killing the engine? Since it idles and then suddenly dies i suspect that you are actuating the blade?
I just figured it out today. What was happening is, the quick disconnect on the hose from the pump was just closing, and dead heading the pump. The flow never got to the relief, it just stopped right at that connector. I took the quick disconnect out of the circuit and adapterized enough to connect the line right to the block and it worked like a charm. !@#$ quick disconnect!
 
Top